Wind power is considered one of the cleanest, most environmentally friendly energy sources presently available, and wind turbines have gained increased attention in this regard. A modern wind turbine typically includes a tower, a nacelle mounted on the tower, a generator positioned in the nacelle, and one or more rotor blades. The one or more rotor blades convert kinetic energy of wind into mechanical energy using known airfoil principles. A drivetrain transmits the mechanical energy from the rotor blades to the generator. The generator then converts the mechanical energy to electrical energy that may be supplied to a utility grid.
The drivetrain may include a gearbox, a rotor shaft, and a generator shaft. More specifically, the rotor shaft may rotatably couple the rotor blades to the gearbox. The generator shaft may rotatably couple the gearbox to the generator. In this respect, the drivetrain and, in particular, the gearbox may allow the generator to rotate at a different speed than the rotor blades.
During operation of the wind turbine, the rotor blades exert torque on the rotor shaft. The magnitude of the torque exerted on the rotor shaft may be useful in determining various operating and performance characteristics of the wind turbine. For example, the torque exerted on the rotor shaft may be used when determining the wind speed, the load on a drivetrain of the wind turbine, the electrical power generated by the wind turbine, and/or the power losses occurring in the wind turbine.
Conventional systems and methods for determining the torque exerted on the rotor shaft may provide unreliable torque determinations. For example, some conventional systems and methods determine the torque exerted on the rotor shaft based on measurements taken from the generator. These systems and method do not account for losses in the gearbox and are prone to error. Systems and methods that use strain gauges placed on the rotor shaft to determine the torque exerted thereon are also inaccurate. Furthermore, determining the torque on the rotor shaft based off of electrical characteristics of the wind turbine (e.g., measured electrical power) is also unreliable.
Accordingly, improved wind turbines, and, in particular, improved systems and methods for determining the torque exerted on wind turbine shafts, are desired in the art. Specifically, systems and methods that produce relatively more reliable torque determinations would be advantageous.